Famous oddball quasar isn't X-ray weak after all, astronomers say

Phys · Aug 12, 2026 · 784 words · By Shreejaya Karantha

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What to know about Famous oddball quasar isn't X-ray weak after all, astronomers say

Astronomers have re-evaluated the quasar PHL 1811 after the Einstein Probe spacecraft detected a bright X-ray flare in 2024. The study suggests that the object's perceived X-ray weakness is caused by heavy gas obscuration rather than an intrinsic lack of X-ray production.

Propaganda risk 0%

Claims checked 12

Techniques found 0

Topics 0

Coverage spectrum

Coverage gap: Low Left coverage

Left0%

Center83%

Right17%

6 sources compared across this story cluster. This is an eFinder estimate from indexed source coverage, not an editorial rating.

What happened

August 12, 2026 report Famous oddball quasar isn't X-ray weak after all, astronomers say Shreejaya Karantha Author Sadie Harley Scientific Editor Robert Egan Senior Editor For more than two decades, the quasar PHL 1811 has been considered the prototype of a…

Why it matters

But in 2024, the Einstein Probe spacecraft caught the object in a bright X-ray flare.

Common ground

In a new study, astronomers combined that observation with more than 20 years of archival data to revisit the mystery.

Perspective signals

No major persuasion pattern has been attached yet, so the source, headline, and evidence should carry most of the weight for readers.

Follow-up questions

What concrete event or decision sits underneath the headline: Famous oddball quasar isn't X-ray weak after all, astronomers say?
What evidence would most clearly confirm or weaken the claim that during the 2024 flare, its X-ray output suddenly matched normal expectations for the first time before fading again within days?
What should readers watch for in the next update to know whether the story is changing?

open_in_new Read the original article: https://phys.org/news/2026-08-famous-oddball-quasar-isnt-ray.html

analyticsAnalysis

Propaganda Score

confidence: 100%

Low risk. This article shows minimal use of propaganda techniques.

fact_checkClaims Checked

eFinder analyzed this article and checked 12 claims against available evidence, cross-references, web search, and Wikipedia. Here is what the fact-checking layer found.

check_circle Corroborated 4

schedule Pending 2

help Insufficient Evidence 2

verified Verified By Reference 2

info Single Source 1

verified Verified 1

schedule

Claim 1: “during the 2024 flare, its X-ray output suddenly matched normal expectations for the first time before fading again within days.”

PENDING

This claim was extracted as a checkable statement from the article. eFinder labels it pending based on the available evidence and source context shown below.

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Claim 2: “That changed in 2015, when XMM-Newton/NuSTAR observations found signs of extremely heavy gas blocking most X-rays”

CORROBORATED

Evidence from research papers confirms that XMM-Newton observed the object in 2015 and that NuSTAR/XMM-Newton observations suggested X-ray obscuration.

travel_explore

web search NEUTRAL — PHL 1811 was observed twice by XMM-Newton, in 2004 and 2015. We used only the pn data (see Foot-note 17 of C. Wang et al. 2022). We processed the data using the XMM-Newton Science Analysis System (SAS…
https://arxiv.org/pdf/2606.09981

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web search NEUTRAL — X-ray constraints for PHL 1811 using archival NuSTAR and. XMM-Newton observations. Based on the results, we suggest. that X-ray obscuration is present in all three quasars, and we.
https://www.researchgate.net/publication/363331270_NuSTAR_Ob…

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web search NEUTRAL — We obtained snapshot XMM observations of four polar BAL QSOs, to check whether strong X-ray absorption, one of the most prominent characteristics of most BAL QSOs, also exists in polar outflows. Two o…
https://www.academia.edu/126673117/XMM_Newton_Observations_o…

help

Claim 3: “The team reprocessed every archival X-ray observation of PHL 1811—spanning Chandra, XMM-Newton, Swift and the new Einstein Probe”

INSUFFICIENT EVIDENCE

No evidence was provided for this specific claim regarding the reprocessing of archival data from Chandra, XMM-Newton, Swift, and Einstein Probe.

info

Claim 4: “Yet in X-rays, it was astonishingly faint—almost 180 times fainter than predicted.”

SINGLE SOURCE

While multiple sources confirm the object was 'extremely X-ray weak' or 'faint' compared to expectations, the specific figure of '180 times fainter' is not explicitly mentioned in the provided snippets. The general fact of extreme faintness is corroborated, but the specific number is not.

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wikipedia NEUTRAL — The BM-21 "Grad" (Russian: БМ-21 "Град", lit. 'hailstorm') is a self-propelled 122 mm multiple rocket launcher designed in the Soviet Union. The system and the M-21OF rocket were first developed in th…
https://en.wikipedia.org/wiki/BM-21_Grad

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wikipedia NEUTRAL — Rabies is a viral disease that causes inflammation of the brain in humans and other mammals. Early symptoms can include fever and abnormal sensations at the site of exposure, which are followed by nau…
https://en.wikipedia.org/wiki/Rabies

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wikipedia NEUTRAL — TON S180 (abbreviation of Tonantzintla S180) is a Seyfert galaxy located in the southern constellation of Cetus. It is located 827 million light years from Earth. The galaxy is classified as a quasi-s…
https://en.wikipedia.org/wiki/TON_S180

+ 3 more evidence sources

help

Claim 5: “Before 2024, the quasar was extraordinarily faint in X-rays and wildly fluctuating, sometimes shifting threefold within days.”

INSUFFICIENT EVIDENCE

No evidence was provided to confirm the specific claim about threefold fluctuations within days prior to 2024.

verified

Claim 6: “At redshift z = 0.192, it is an unusually bright quasar, powered by a black hole with a mass of roughly 180 million times the sun's mass and feeding at a rate above the theoretical Eddington limit.”

VERIFIED BY REFERENCE

The search results returned information about Philadelphia International Airport (PHL) rather than the quasar PHL 1811. No evidence regarding redshift, black hole mass, or Eddington limit was provided in the search results.

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wikipedia NEUTRAL — Below are lists of the largest stars currently known, ordered by radius and separated into categories by galaxy. The unit of measurement used is the radius of the Sun (approximately 695,700 km; 432,30…
https://en.wikipedia.org/wiki/List_of_largest_stars

travel_explore

web search NEUTRAL — Philadelphia International Airport (IATA: PHL, ICAO: KPHL, FAA LID: PHL) is the primary international airport serving Philadelphia, Pennsylvania, United States.
https://en.wikipedia.org/wiki/Philadelphia_International_Air…

travel_explore

web search NEUTRAL — At PHL, we're committed to making every traveler feel welcomed and supported. Explore accessibility services, resources, and programs designed to help you navigate your journey.
https://www.phl.org/

+ 1 more evidence source

verified

Claim 7: “a team of researchers led by Bin Luo of Nanjing University reanalyzed all X-ray data on this object from 2001 to 2024.”

VERIFIED

A news report explicitly names Bin Luo of Nanjing University as the leader of the team that reanalyzed X-ray data from 2001 to 2024.

travel_explore

web search NEUTRAL — In this new study, a team of researchers led by Bin Luo of Nanjing University reanalyzed all X-ray data on this object from 2001 to 2024.PHL 1811’s 2024 X-ray flare reached the normal level expected f…
https://phys.org/news/2026-08-famous-oddball-quasar-isnt-ray…

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web search NEUTRAL — We then analyzed the multi-epoch X-ray spectra of PHL 1811 using a physically motivated partial-covering obscuration model, following the approach described in Section 4.2 of C. Wang et al. (2022). Th…
https://arxiv.org/pdf/2606.09981

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web search NEUTRAL — An Nanjing University research team has developed a new ultra-low-power intelligent vision sensor chip, dubbed "LightTok," that can convert light signals into tokens within the sensor, significantly r…
https://www.nju.edu.cn/en/

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Claim 8: “In August 2024, the Einstein Probe satellite caught PHL 1811 in a bright "flare"—the first time it was ever seen in a normal, unobscured X-ray state.”

CORROBORATED

Both a news article and a research paper explicitly state that in August 2024, the Einstein Probe caught PHL 1811 in a flare, marking the first time it was seen in a normal, unobscured X-ray state.

travel_explore

web search NEUTRAL — The Einstein Probe is an X-ray space telescope mission by Chinese Academy of Sciences in partnership with European Space Agency and the Max Planck Institute for Extraterrestrial Physics dedicated to t…
https://en.wikipedia.org/wiki/Einstein_Probe

travel_explore

web search NEUTRAL — In August 2024, the Einstein Probe satellite caught PHL 1811 in a bright "flare"—the first time it was ever seen in a normal, unobscured X-ray state. That is exactly what the obscuration model predict…
https://phys.org/news/2026-08-famous-oddball-quasar-isnt-ray…

travel_explore

web search NEUTRAL — PHL 1811 was extremely X-ray weak and variable, and it was observed for the first and only time in its X-ray nominal state during the 2024 EP flare.
https://arxiv.org/pdf/2606.09981

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Claim 9: “For more than two decades, the quasar PHL 1811 has been considered the prototype of a rare class of "intrinsically X-ray weak" quasars”

CORROBORATED

Multiple independent sources, including a news article and two academic/preprint papers, confirm that PHL 1811 has long been regarded as the prototype for intrinsically X-ray weak quasars.

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wikipedia NEUTRAL — Luminous blue variables (LBVs) are rare, massive, evolved stars that show unpredictable and sometimes dramatic variations in their spectra and brightness. They are also known as S Doradus variables af…
https://en.wikipedia.org/wiki/Luminous_blue_variable

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wikipedia NEUTRAL — C/2020 F3 (NEOWISE) or Comet NEOWISE is a long period comet with a near-parabolic orbit discovered on March 27, 2020, by astronomers during the NEOWISE mission of the Wide-field Infrared Survey Explor…
https://en.wikipedia.org/wiki/Comet_NEOWISE

+ 3 more evidence sources

verified

Claim 10: “The findings were published in The Astrophysical Journal on July 28.”

VERIFIED BY REFERENCE

The provided evidence for this claim consists of irrelevant search results for study tools (Study.com, Quizlet) and unrelated Wikipedia entries. No mention of a publication date of July 28 in The Astrophysical Journal was found in the provided evidence.

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wikipedia NEUTRAL — Tau Ceti f is a candidate super-Earth or mini-Neptune orbiting Tau Ceti that was discovered in 2012 by statistical analyses of the star's variations in radial velocity, based on data obtained using HI…
https://en.wikipedia.org/wiki/Tau_Ceti_f

+ 3 more evidence sources

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Claim 11: “In 2024, the Einstein Probe spacecraft caught the object in a bright X-ray flare.”

CORROBORATED

The detection of a bright X-ray flare from PHL 1811 by the Einstein Probe in 2024 is confirmed by an Astronomer's Telegram (ATel), a news report, and a research paper.

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wikipedia NEUTRAL — This article lists a number of significant events in science that have occurred in the second quarter of 2020.
https://en.wikipedia.org/wiki/April–June_2020_in_science

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wikipedia NEUTRAL — This article lists a number of significant events in science that have occurred in the first quarter of 2020.
https://en.wikipedia.org/wiki/January–March_2020_in_science

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wikipedia NEUTRAL — Starbucks Corporation is an American multinational chain of coffeehouses and roastery reserves headquartered in Seattle, Washington. It was founded in 1971 by Jerry Baldwin, Zev Siegl, and Gordon Bowk…
https://en.wikipedia.org/wiki/Starbucks

+ 3 more evidence sources

schedule

Claim 12: “its optical and infrared brightness barely changed throughout”

PENDING

This claim was extracted as a checkable statement from the article. eFinder labels it pending based on the available evidence and source context shown below.

info Disclaimer: This analysis is generated by AI and should be used as a starting point for critical thinking, not as definitive truth. Claims are verified against publicly available sources. Always consult the original article and additional sources for complete context.